Regulating CsPbI₃ crystal growth for efficient printable perovskite solar cells and minimodules

Large pinhole-free, high-crystal-quality perovskite films are the key to realizing efficient, stable CsPbI₃ perovskite modules. In this work, we use the crystal growth modulation strategy to prepare high-quality CsPbI₃ films from small to large sizes using a new precursor solution with CsI/DMAPbI₃/PbI₂ in a DMAAc/DMF mixed solvent (DMAAc: dimethylamine acetate). The champion small-size CsPbI₃ device presents a photoelectric conversion efficiency (PCE) above 21% and a certified PCE of 20.05%, and the best blade-coated CsPbI₃ minimodule exhibits a PCE of 18.3% for an aperture area of 12.39 cm² and a PCE of 19.9% for an active area of 11.40 cm². In addition, the composition engineering of the precursor solution toward CsPbI₃ crystallization is explored: the DMAAc/DMF mixed solvent can facilitate phase transformation and reduce the nucleation rate, and the mixture of PbI₂ and DMAPbI₃ will further improve the film microstructure and uniformity. Consequently, the anti-humidity stability and phase stability of the CsPbI₃ films are greatly improved, and the corresponding devices exhibit good operational stability. CsPbI₃ modules with simple encapsulation also present excellent long-term storage stability over 150 days. This crystal growth regulation strategy provides a new method to produce large-scale CsPbI₃ and even hybrid perovskite solar cells for future commercialization.